CONICET | Buscador de Institutos y Recursos Humanos

Chronic exposure to arsenic, an environmental toxicant, is associatedwith skin alterations. Arsenic affects the normal balance ofkeratinocyte proliferation and death by compromising mitochondrialfunction. Mitochondrial damage is compensated by mitochondrialbiogenesis and increased mitochondrial mass (MM). Dopamine(DA) is a neurotransmitter that modulates the immune system. Keratinocytessynthesize and degrade DA and express DA receptors.Objective: Here we explored the effect of arsenic trioxide (ATO)and DA on mitochondrial membrane potential (MMP), mitochondrialmass (MM), and cell death in the human keratinocyte cell lineHaCaT. Methods: HaCat cells were exposed to increasing dosesof ATO or/and DA for 48h and stained with nonyl-acridine orange(NAO) to evaluate MM, tetramethylrhodamine-ester (TMRE) to evaluateMMP, and propidium iodide (PI) to evaluate cell viability. Thesamples were analysed by flow cytometry. Results: ATO causeda dose-dependent linear increase in MM within the range 5μM to30μM (slope =0.147; R2=0.982), a dose-dependent linear decreasein MMP (slope=-9.955; R2=0.979). At 30μM the cell death rate was35% (SE=1.57%). When cells where exposed to DA alone a lineardose-dependent decrease in MM was observed, particularly withinthe range 0.1nM-1μM (slope=-0.24: R2=0.73). No changes were observedin cell viability and MMP up to 100 μM DA. When ATO wascombined with 100μM DA a similar pattern of change was observedwith a dose dependent increase of MM, decrease of MMP and increasedkeratinocyte death. At 30 μM the cell death rate was 40%(SE=0.18). Conclusion: At doses above 5μM, ATO caused mitochondrialdamage, increased MM and cell death in HaCat keratinocytes.The increase in MM may indicate that mitochondrial biogenesiswas a protective response against ATO toxicity. DA decreasedMM with no effect on viability, but increased ATO-induced cell deathin keratinocytes.